Same issue here but no idea what the solution is

Same issue here but no idea what the solution is

Hi,
as always it helps to see that others have the same issues. Unfortunately I do not see a solution (also not on STackOverflow). Would be really great if someone would have the kindness to explain what the cause and the solution of the problem is. Since it seems to come from ExtJS any input from Sencha Experts would be greatly appreciated.
Thanks